Remote signaling system



June 2, 1936. A. J-. JOHNSTON 2,042,532

REMOTE SIGNALING SYSTEM Filed March 27, 1934 Inventor: Arbh w J. Johnston,

LN 5. 19M Pieter-neg.

Patented June 2, 1936 PATENT OFFlC REMOTE SIGNALING SYSTEM Arthur J. Johnston,

Aldan, Pa., assignor to General Electric Company, a corporation of New York Application March 27,

10 Claims.

In accordance with my invention, I provide an improved arrangement of apparatus at the remote station whereby, in response to the flow of the ringing current after a telephone connection has been established with a telephone at the reordinary telephone systems, a telephone transmitter at the remote station is 'to transmit audible signals over the established telephone connection to the calling station and predetermined audible signals are produced at said transmitter in accordance with the conditions of the various positions of apparatus at the remote station.

My invention will be better understood from the following description when taken in connection with the accompanying drawing the single figure of which is a diagrammatic illustration of a remote signaling system embodying my invention and its scope will be pointed out in the appended claims.

Referring to the drawing, I represents a station at which there are a'number of pieces of apparatus which it is desired a person, such as a dispatcher, should check occasionally to determine whether or not they are in operation. In the particular embodiment of my invention illustrated, the pieces of apparatus at the station .I are circuit breakers 2, 3 and 4, the positions of which are to be checked by my improved arrangement of apparatus but it will be obvious to those skilled in the art that my invention may be employed to check the position. of any other device at the station.

At the station I there is also provided an ordinary telephone set 5 which is connected by the telephone wiresfi to a telephone exchange I so that a telephone connection can be established in the usual manner between any other telephone set on the telephone system, suchfor example as a telephone set 8 located at a dispatchers office, and the telephone set 5 at the station I.

Associated with the telephone wires 6 at the remote station I is a relay I which is connected to the wires in such a manner that the relay operates to close its contacts II when ringing current is supplied through the wires 6 to the telephone set 5. The closing of the contacts iI efiects the energization of the relay l2 which, in

1934, Serial No. 717,598

turn, establishes a telephone connection between a telephone transmitter I3 at the remote station and the telephone wires 6. The energization of the relay I2 also starts suitable switching means into operation so that predeterminedaudible si nals are produced at the transmitter I3 inaccordance with the positions of the circuit breakers 2-4 inclusive. Inthe arrangement shown, signals of three different characters are produced at the transmitter I3, namely, a high pitch signal by an electric horn I4, a low pitch signal by occupied by the circuit breakers 2-4 inclusive is effected by the selector switches 20 and 2 I. While these selector switches may be of any suitable which are well known in the art, I have shown two switches of the well known rotary type each of which consists of five banks of twenty-five stationary contacts and each bank having a cooperating wiper associated therewith. The five wipers of each switch are mounted on a common shaft and are adapted to move in a step'by step manner over the stationary contacts of the respective banks in response to the dewerg'ization of an associated motor magnet.

The switch 20 constitutes a code sender which is so connected that each time the wipers thereof are moved into engagement with all of the contacts of the respective banks the signals I4, I5 and I6 are operated in a predetermined manner dependlng upon the positions of the switch 2I and the circuit breakers 2-4 inclusive. The position of the switch 2|, in turn, depends upon the positions of the circuit breakers 2-4 inclusive.

Normally the switches 20 and II are in the positions shown. When the relay I2 is energized in response to a telephone call to the station I, the switch 2| is moved to its position I and the switch 20 is operated so that its movable contacts engage all of their respective stationary contacts thereby operating the signals I4, I5 and IS in a. manner to indicate whether or not all of the circuit breakers are closed. If all of the circuit breakers are closed, the high pitch signal I4 is operated three times whereas if any one of the circuit breakers is opened, the high pitch signal I4 is operated only two times. The bell I6 is then operated to indicate that the code signal has been completed.

If all of the circuit breakers are closed at the time the switch 20 operates, this switch stops in its normal position and the switch 2| is then restored. to its normal positionand no further signals are transmitted through the transmitter |3. While the switch 2| is being restored to its normal position, a circuit is completed to effect the deenergization of the relay l2 so as to disconnect the transmitter |3 from the telephone wires 6 and to reconnect the telephone set 5 thereto. If, however, any one of the circuit breakers 2-4 inclusive is open, the switch 2|, instead of being immediately restored to its normal position stops in one of its positions which is individual to the open circuit breaker and then the switch 20 operates again to transmit a predetermined signal corresponding to the open circuit breaker. The switch 2| then moves to another position which is also individual to the open circuit breaker where it remains while the switch 20 again operates to repeat the code corresponding to the open circuit breaker.

If more than one circuit breaker is open, the switch 2| also stops in two different positions individual to each of the open circuit breakers and while stopped in any such position the switch 20 operates to transmit a signal individual to the corresponding open circuit breaker.

Having described in general the apparatus employed in the operation of my system, the details of operation will now be given in order to explain the invention more fully.

It will be assumed that a dispatcher desires to ascertain a condition of the circuit breakers 2-4 inclusive at the remote station I. In order to do this the dispatcher will make a call for the remote station through the ordinary telephone system either by calling an operator at the telephone exchange or by dialing the number or the telephone at the remote station so as to operate suitable automatic equipment at the telephone exchange depending upon whether the telephone system is of the manual or the automatic switching type. When the telephone connection has been established between the calling station 8 and the telephone wire 6 leading to the remote station, alternating current ringing current flows through the 'wire 5. This alternating current flows through the winding of relay l0 which, when closing its contacts completes through the resistor 23 an energizing circuit for the windin of relay l2. By closing its contacts 24 the relay l2 completes a shunt circuit around the contacts ll of relay III so that the subsequent opening of the contacts does not deenergize the relay |2. By opening its contacts 25 and closing its contacts 26 the relay |2 disconnects the telephone set 5 from the telephone wires 6 and connects the transmitter |3 thereto so that the transmitter is in an operative condition to transmit audible signals produced thereat over the established telephone connection. The connection of the transmitter |3 to the wires 6 causes in a well known manner the flow of ringing current to stop through the wires |6 so that the relay I0 becomes deenergized and opens its contacts By closing its contacts 21 the relay |2 completes a circuit for the motor magnet 39 of the switch 2| so that the switch moves from its normal position to its position I. This energizing circuit is from one side of a suitable control circuit through the contacts 21 of relay I2, conductor 3|, normal contact and wiper of bank 0 of switch 2|, winding of motor magnet 30, contacts 33 of the motor magnet 30, conductor 34, normal contact and wiper of bank e of switch 20 to the'other side of the control circuit. An energizing circuit is also completed for relay 35 through the wiper and. normal contact of bank c of switch 2|, conductor 3|, and contacts 21 of relay |2. The relay 35 is arranged in any suitable manner so that when it is energized it opens its contacts 36 immediately but when it is deenergized its contacts 36 do not close until a 5 predetermined time after the relay is deenergized. When the switch 2| reaches its position I, the switch remains in this position since the circuit of the motor magnet 30 is now open. After the switch 2| has remained in its position I for a 10 predetermined time, the relay 35 closes its contacts 36 and completes an energizing circuit for a time delay relay 31. This circuit is from one side of a suitable control circuit through the winding of relay 31, contacts 38 of motor magnet 39 of 15 switch 20, wiper and normal contact of bank b of switch 20, conductor 40, contacts 36 of relay 35, wiper and first oil-normal contact of bank b of switch 2| to the other side of the control circuit. Relay 31 after being energized a prede- 20 termined time closes its contacts 4| and completes an energizing circuit for the motor magnet 39 of the switch 20. Motor magnet 39 by opening its contacts 38 effects the deenergization of relay 31 which, in turn, by opening its con- 25 tacts 4| effects the deenergization of the motor magnet 39 which then moves the switch 20 from its normal position to its position I. Since all of the stationary contacts of the bank b of switch 2|) except the normal stationary contact of this 30 bank are connected to the one side of the control circuit, the switch 20 now moves step by step from its position I through its other positions until it reaches its normal position. The speed at which the switch 20 is operated depends upon the 3 time setting of the time relay 31.

While the switch 20 is in its positions l3, the circuit is completed for the high pitch horn. l4. This circuit also includes the first oil-normal contact and wiper of bank a of switch 2|. When the 40 switch 20 is in its position I5, a circuit is also completed for the high pitch horn M if all of the circuit breakers 2-4 inclusive are closed so that all of the auxiliary relays 43, 44 and 45 which are respectively associated with these circuit breakers 15 are energized. This circuit is from one side of the control circuit through the winding of the horn l4, wiper and fifteenth off-normal contact of bank a of switch 2|], conductor 46, contacts 41 of relay 43, contacts 48 of relay 44, contacts 49 of relay 45 to the other side of the control circuit.

If, however, any one of the circuit breakers is open, the auxiliary relay associated with the circuit breaker is deenergized and the above described circuit for the high pitch horn I4 is not completed in position |5 of the switch 20. Therefore, under these conditions the high pitch signal is operated only twice.

When the switch 20 is in its twenty-third position, a circuit is completed for the control relay 60 50 from one side of the control circuit through the winding of relay 50, conductor 5|, wiper and first off-normal contact of bank e of switch 2|, conductor 52, twenty-third oil-normal contact and wiper of bank e of switch 20 to the other side of the control circuit. By closing its contacts 53 the relay 50 completes a locking circuit for its ope-rating winding through conductor 54 and the first off-normal contact and wiper of bank d of switch 2|. Therefore, the relay 50 remains energized when the switch 20 leaves its position 23.

When the switch 20 reaches its position 24, a circuit is completed for the bell l6 which, by operating, indicates that the signal corresponding 7.

to the positions of the circuit breaker has been completed. 7

When the switch 20 again reaches its normal position, a circuit is completed for the motor magnet 30 of the switch 2|. This circuit is from one side of the control circuit, through contacts 55 of relay 50, conductor 56, first ofi-normal contact and wiper of bank 0 of switch 2|, winding of motor magnet 3|], contacts 33 of motor magnet 36, normal contact and wiper of bank e of switch 20 to the other side of the control circuit. The motor magnet 30 then operates in a manner well known in the art to move the switch 2| from position I to position 2.

As soon as switch 2| leaves its position I, the relay 5!] is deenergized as the circuit of this relay is interrupted by the wiper of bank d of switch 2| leaving its first ofi-normal contact.

If the circuit breaker 2 is closed so that its auxiliary relay 43 is energized when the switch 2| reaches its position 2, a circuit is immediately completed for the motor magnet 30 of switch 2| to effect the movement of this switch from its position 2 to its position 3. This circuit is from one side of the control circuit through contacts 63 of relay 43, conductor 64, second off-normal contact and wiper of bank 0 of switch 2| winding of motor magnet 32, contacts 33 of motor magnet 30, conductor 34, normal contact and wiper of bank e of switch 22 to the other side of the control circuit. A circuit is also completed from the wiper of bank 0 of switch 2| through the winding of relay 35 so that this relay maintains its contacts 36 open in order to prevent the switch 20 from being moved from its normal position.

If the circuit breaker 2 is open so that its auxiliary relay 43 is deenergized when the switch 2| is in its position 2, the switch 2| stops in this position 2 and after it has remained in this position for a predetermined time, the relay 35 closes its contacts 36 and completes through the wiper and second off-normal contact of bank b of switch 2| an energizing circuit for the time relay 31. Relay in then effects the operation of the switch 26 through all of its positions in the manner above described. When the switch 20 is in its positions I, 3 and l, a circuit is completed for the low pitch signal |5 through the bank 0 of the switch 20, conductor 58 and second oiT-normal contact and wiper of bank a of switch 2|. Therefore, the low pitch signal is operated twice with a short time interval between the two operations and then again after a relatively long time interval, this being the code corresponding to the open circuit breaker 2.

When the switch 20 reaches its position 23, a circuit is completed for the winding of relay 43. This circuit is from one side of the control circuit through the winding of relay 43, conductor 60, second oiT-normal contact and wiper of bank e of switch 2 I, conductor 52, twenty-third oiT-normal contact and wiper of bank e of switch 20 to the other side of the control circuit.

By closing its contact 6| the relay 43 completes a locking circuit for its winding through conductor 62 and the second off-normal contact and wiper of bank (1 of switch. 2| so that this relay remains energized while the switch 20 is moving from its position 23 through its position 24 to its normal position.

By closing its contacts 63 the relay 43 completes an energizing circuit for the relay 35 through conductor 64 and the second off-normal contact and wiper of the bank 0 of switch 2|.

positions I When the switch 20 .is'in its position 24, a circuit is completed for the bell IS. The operation of this bell indicates that the code corresponding to the open circuit breaker 2 has been completed.

When the switch 20 again reaches its normal position, a circuit is completed for the motor magnet 30 to effect the movement of the switch 2| from its position 2 to its position 3. This circuit is from one side of the control circuit through contacts 63 of relay 43, conductor 64, second 01T- normal contact and wiper of bank 0 of switch 2|, winding of motor magnet 30, contacts 33 of motor magnet 30, conductor 34, normal contact and wiper of bank e of switch 20 to the other side of the control circuit.

When the switch 2| leaves its position 2, the relay 43 is deenergized as the circuit of this relay is interrupted by the wiper of the bank d of switch 2| leaving its second oil-normal contact if at the same time the circuit breaker 2 is opened.

When the circuit breaker 3 is closed so that its auxiliary relay 44 is energized when the switch 2| is in its position 3, a circuit is immediately completed for the motor magnet 36 of the switch 2| to effect the movement of this switch from its position 3 to its position 4. This circuit is from one side of the control circuit through contacts 53 of relay 44, conductor 6?, third ofi-normal contact and wiper of bank 0 of switch 2 winding of motor magnet 30, contact-s33 of motor magnet 36, conductor 34, normal contact and wiper of bank e of switch 20 to the other side of the control circuit. A circuit is also completed for the winding of relay 35 from the wiper of bank 0 of switch 2| so that this relay maintains its contacts 36 open in order to prevent the switch 28 moving from its normal position;

If the circuit breaker 3 is open so that its auxiliary relay 44 is deenergized when the switch 2| reaches its position 3, this switch stops in this position 3 and after it has remained in this position for a predetermined time, the relay 35 closes its contacts 36 and completes through the wiper and third off-normal contact of bank h of switch 2| an energizing circuit for the time relay 3?. Relay 3'! then effects the operation of the switch 23 through all of its positions in the same manner as above described. When the switch 24 is in its I3, and IS, a circuit is completed for the low pitch signal l5 through the bank 0 of the switch 20, conductor 69 and the third offnormal contact and wiper of bank a of switch 2|. Therefore, the low pitch signal is operated four times with a short time interval between the first and second signals and the thirdand fourth signals and a relatively long time interval between the second and third signals, this being the code corresponding to the open circuit breaker 3.

When the switch 20 reaches its position 23 a circuit is completed for the winding of relay 44. This circuit is from one sideof the control circuit, through the Winding of relay 44, conductor H3, third off-normal contact and wiper of bank e of switch 2|, conductor 52, twenty-third o ifnormal contact and wiper of bank e of switch 20 to the other side of the control circuit.

By closing its contacts H, the relay 44 cornpletes a locking circuit for its winding through conductor 13 and the third off-normal contact and Wiper of bank (I of switch 2| so that this relay remains energized while the switch 22 is moving from its position 23 to its normal position.

By closing its contacts 6% the relay 44 completes an energizing circuitfor the relay 35 through conductor 61 and the third off-normal contact and wiper of bank of switch 2|.

When the switch 20 is in its position 24, a circuit is completed for the bell IS. The operation of this bell indicates that the code corresponding to the open circuit breaker 3 has been completed.

When the switch 20 reaches its normal position, the above-traced circuit for the motor ma net 3i3 is completed through the contacts 66 of the relay 44 to effect the movement of the switch 2| from its position 3 to its position 4. When the switch 2| leaves its position 3, relay 44 is deenergized as the circuit of this relay is interrupted by the wiper of bank d of switch 2| leaving its third off-normal contact if at the same time the circuit breaker 3 is open.

If the circuit breaker 4 is closed so that its auxiliary relay 45 is energized when the switch 2| reaches its position 4, a circuit is immediately completed for the motor magnet 30 of the switch 2| to effect the movement of the switch from its position 4 to its position 5. This circuit is from one side of the control circuit through contacts 14 of relay 45, conductor 15, fourth off-normal contact and wiper of bank c of switch 2 I, winding of motor magnet 30, contacts 33 of motor magnet 30, conductor 34, normal contact and wiper of bank e of switch 20 to the other side of the control circuit. A circuit is also completed from the wiper c of bank 2| through the winding of relay 35 so that this relay maintains its contacts 36 open and thereby prevents the switch 20 from moving from its normal position.

If the circuit breaker 4 is open so that its auxiliary relay 45 is deenergized when the switch 2| reaches its position 4, the switch 2| stops in this position and after it has remained there for a predetermined time, the relay .35 closes its contacts 36 and completes through the wiper and the fourth off-normal contact of bank b of switch 2| an energizing circuit for the time relay 31. Relay 3! then effects the operation of the switch. 2|] through all of its positions in the same manner as above described. When the switch 20 is in its positions I, 3, and 9, a circuit is completed for the low pitch signal |5 through the bank (2 of the switch 20, conductor 16 and the fourth -normal contact and wiper of bank a of switch 2|. Therefore, the low pitch signal is operated four times with a short time interval between the first and second and the second and third signals and a relatively long time interval between the third and fourth signals, this being the code corresponding to the opening of the circuit breaker 4.

When the switch 20 reaches its position 23, a circuit is completed for the winding of relay 45, this circuit being from one side of the control circuit through the winding of relay 45, conductor Ti, fourth off-normal contact and wiper of bank e of switch 2|, conductor 52, twenty-third off-normal contact and wiper of bank e of switch 26 to the other side of the control circuit.

By closing its contacts 18 the relay 45 completes a locking circuit for its winding through the conductor 19 and the fourth off-normal contact and wiper of bank d of switch 2| so that this relay remains energized while the switch 20 is moving from its position 23 to its normal position.

By closing its contact 14 the relay 45 completes an energizing circuit for the relay 35 through the conductor and the fourth off-normal contact and wiper of bank c of switch 2|.

When the switch is in its position 24, a cirit disconnects the transmitter cuit is completed for the bell l6 so that it' is operated to indicate that the code corresponding to the circuit breaker 4 has been completed.

When the switch 20 reaches its normal position, the circuit above described is completed for the motor magnet 3!! to effect the movement of the switch 2| from its position 4 to its position 5.

Since the fifth off-normal contacts of banks a, c, d, e of switch 2| are respectively connected to the first off-normal contacts of these banks and the sixth, seventh and eighth off -normal contacts thereof are respectively connected to the fourth off-normal contacts that the switches 20 and 2| are operated so as to repeat once the signals which were produced while the switch I2 is moving from its position I to its position 5.

After the switch 2| reaches its position 9, a circuit is completed for the motor magnet of switch 2| and for the winding of relay through the wiper and the ninth to the twenty-fourth off-normal contacts inclusive of bank 0 of switch 2| to effect the movement of this switch from its position 9 to its normal position and to prevent the operation of the switch 28 during this operation of the switch 2|.

While switch 2| is in its position 24, a circuit is completed from one side of the control circuit through the wiper and the twenty-fourth offnormal contact of bank d of switch 2|, conductor 89, resistor 23, contacts 24 of relay |2 to the other side of the control circuit. Since this circuit shone-circuits the winding ,of the relay I2, this relay becomes deenergized and by opening its contacts 2t and 21 and by closing its contacts 25,

I3 from the telephone wires 6 and reconnects the telephone set 5 thereto. lhis causes the apparatus at the telephone exchange i to disconnect in a well known manner the telephone connection between the telephone set 8 and the dispatchers office and the telephone set 5 and the control station.

While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the artand I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a signaling system, a dispatchers office, a remote station, means including a public telephone system for establishing a telephone connection between said office and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, means responsive to said ringing current for producing at said transmitter in a predetermined sequence audible codes corresponding to the position of each device.

2. In a signaling system, a dispatchers oflice, a remote station, means including a public telephone system for establishing a telephone connection between said oflice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current second, third or thereof, it is evident for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, and means responsive to said ringing current for producing at said transmitter in a predetermined sequence audible codes corresponding to the position of each device, and for repeating a predetermined number of times said codes in said predetermined sequence.

3. In a signaling system, a dispatchers ofiice, a remote station, means including a public telephone system for establishing a telephone connection between said ofiice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, and means responsive to said ringing current for first producing at said transmitter an audible code depending upon the relative positions of all of said devices and then producing at said transmitter in a predetermined sequence audible codes corresponding to the positions occupied by certain of said devices.

4. In a signaling system, a dispatchers oflice, a remote station, means including a public telephone system for establishing a telephone connection between said ofiice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, and means responsive to said ringing current for producing at said transmitter a predetermined audible code if all of said devices are in their normal positions and a dififerent predetermined audible code if any one of said devices is not in its normal position and for then producing at said transmitter in a predetermined sequence audible codes corresponding to the positions of each device which is not in its normal position.

5. In a signaling system, a dispatchers office, a remote station, means including a public telephone system for establishing a telephone connection between said ofiice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, and means responsive to said ringing current for first producing at said transmitter an audible code depending upon the relative positions of all of said devices and then producing at said transmitter a predetermined number of times in a predetermined sequence audible codes corresponding to the positions occupied by said devices.

6. In a signaling system, a dispatchers oifice, a remote station, means including a public telephone system for establishing a telephone connection between said oilice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, a plurality of devices at said station, each device having a plurality of positions, and means responsive to said ringing current for producing at said transmit-- ter a predetermined audible code if all of said devices are in their normal positions and a different predetermined audible code if any one of said devices is not in its normal position and for then producing at said transmitter a predetermined number of times in a predetermined sequence audible codes corresponding to the position of each device which is not in its normal position.

7. In a signaling system, a dispatchers office, a remote station, means including a public telephone system for establishing a telephone connection between said oifice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, a plurality of devices at said station eachdevice having a plurality of positions, a selector switch having a plurality of positions, each of said devices being individual to a diiferent position of said switch, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, and for causing said switch to occupy its various positions in a predetermined sequence, a code sending switch, and means for causing said code sending switch to produce at said transmitter a code of audible signals individual to the corresponding device when said selector switch is in a position individual to a device and such device occupies a predetermined position.

8. In a signaling system, a dispatchers ofilce, a remote station, means including a public telephone system for establishing a telephone connection between said oflice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, a plurality of devices at said station each device having a plurality of positions, a selector switch having a plurality of positions, each of said devices being individual to a different position of said switch, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection, and for causing said switch to occupy its various positions in a predetermined sequence, a code sending switch, and means for causing said code sending switch to produce at said transmitter a code of audible signals individual to the corresponding device when said selector switch is in a position individual to a device and such device occupies a predetermined position, and to produce no audible signals at said transmitter if the corresponding device occupies a different predetermined position.

9. In a signaling system, a dispatchers ofiice, a remote station, means including a public telephone system for establishing a telephone connection between said ofifice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, a. plurality of devices at said station each device having a plurality of positions, a selector switch having a plurality of positions, certain of said switch positions being individual to a difierent device and another of said switch positions being common to a group of said devices, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection and for causing said selector switch to occupy its various positions in a predetermined sequence, and means for producing at said transmitter a predetermined audible signal if all of said group of devices are in predetermined positions when said switch is positions being common inthe position thereof common to said group and a different predetermined audible signal if any device in said group is in a difierent predetermined position and for producing an audible code individual to the corresponding device of said group when said switch is in the position individual to such device and it is in such a different predetermined position.

10. In a signaling system, a dispatchers ofiice, a remote station, means including a public telephone system for establishing a telephone connection between said ofiice and station and for causing ringing current to flow through said telephone connection, a telephone transmitter at said station, a plurality of devices at said station each device having a plurality of positions, a selector switch having a plurality of positions, certain of said switch positions being individual to a different device and another of said switch to a group of said devices, means responsive to said ringing current for operatively connecting said transmitter to said telephone connection and for causing said selector switch to occupy its various positions in a predetermined sequence, a code sending switch, and means controlled by said selector switch for effecting the operation of said code sending switch to produce at said transmitter a predetermined audible signal when all of said groups of devices are in predetermined positions when said selector switch is in the position thereof comm-on to said group and a different audible signal in such selector switch position if any of said group of devices occupies a diiferent position, and for operating said code sending switch to produce at said transmitter a predetermined audible signal individual to a device in said group only when said selector switch is in the position thereof which is individual to such device and such device is in a predetermined position.

ARTHUR J. JOHNSTON. 

